Steam Siege
This is not everyone’s favourite set by any means, however it did feature some pretty nice cards in my opinion. The box ratios are assumed to be 7.2 holos, 2.4 “regular” Pokémon-EX and 2.4 full arts, as well as 2.4 BREAK cards (in the reverse slot). The relatively low number of ultra rares contributed to the sets unpopularity. With two secret rares, and assuming the overall odds of getting one remains the same, they are assumed to be printed 6 times each on the full arts sheet. The rarity table looks as follows:
The raw data for the holos, rares, Pokémon-EX, full arts/secret rares and BREAK cards is given below; for this set, I also looked at the summary of Derium’s 1,000 pack opening (he did not do one for Fates Collide apparently):
The two non-holo rares featured as theme deck exclusive holos, Volcanion and Hoopa, account for 28 / 666 = 5.09 / 121 rares in the sample; I am thus assuming them both to be R3 cards. This makes them rarer than the holos, which is significant as Volcanion was a very playable card back then. As to the rarest cards in the set, these are now secret rares again since the set includes more than one of them.
Edit 2024/03/24: Changed sequence length from 180 to 360. This has no impact on pull rates.